Quiznetik

Cryptography and Network Security (CNS) | Set 1

1. In symmetric-key cryptography, the key locks and unlocks the box is

Correct : A. same

2. The keys used in cryptography are

Correct : D. all of them

3. Cryptography, a word with Greek origins, means

Correct : B. secret writing

4. A transposition cipher reorders (permutes) symbols in a

Correct : D. block of symbols

5. Network Security provides authentication and access control for resources.

Correct : A. true

6. Which is not an objective of network security?

Correct : D. lock

7. The process of verifying the identity of a user.

Correct : A. authentication

8. Which of these is a part of network identification?

Correct : A. user id

9. The process of transforming plain text into unreadable text.

Correct : B. encryption

10. An algorithm used in encryption is referred to as cipher.

Correct : A. true

11. A process of making the encrypted text readable again.

Correct : A. decryption

12. A person who enjoys learning details about computers and how to enhance their capabilities.

Correct : B. hacker

13. A small program that changes the way a computer operates.

Correct : D. virus

14. An asymmetric-key (or public-key) cipher uses

Correct : B. 2 key

15. We use cryptofraphy term to transform messages to make them secure and immune to

Correct : C. attacks

16. In cryptography , the original message before being transformmed , is called

Correct : B. plain text

17. A straight permutation cipher or a straight p-box has the same number of input as

Correct : C. outputs

18. The man-in-the-middle attack can endanger the security of the diffie-hellman if two parties are not

Correct : A. authenticated

19. Which of the following is not a transport layer vulnerability?

Correct : D. unauthorized network access

20. Transmission mechanisms can be subject to spoofing & attacks based on skilled modified packets.

Correct : A. true

21. TCP/IP model does not have                layer but OSI model have this layer.

Correct : A. session layer

22. In cryptography, what is cipher?

Correct : A. algorithm for performing encrption and decryption

23. In cryptography, the order of the letters in a message is rearranged by

Correct : A. transpositional ciphers

24. What is data encryption standard (DES)?

Correct : A. block cipher

25. Cryptanalysis is used

Correct : A. to find some insecurity in a cryptographic scheme

26. Choose from among the following cipher systems, from best to the worst, with respect to ease of decryption using frequency analysis.

Correct : C. random polyalphabetic , vignere , playfair , plaintext

27. On Encrypting “thepepsiisintherefrigerator” using Vignere Cipher System using the keyword “HUMOR” we get cipher text-

Correct : B. abqdvmwuwjphfvvyyrf znydokvl

28. . Rail Fence Technique is an example of

Correct : B. transposition

29. Public key encryption is advantageous over Symmetric key Cryptography because of

Correct : C. key exchange

30. The sub key length at each round of DES is

Correct : B. 56

31. Which one is the strong attack mechanism?

Correct : C. brute force attack

32. Interception is an attack on

Correct : B. confidentiality

33. Chosen cipher text attack is based on

Correct : A. cryptanalysis

34. The process of writing the text as rows and read it as columns is known as

Correct : C. transposition columnar cipher

35. Biometric authentication works on the basis of

Correct : A. human characteristics

36. Which layer filters the proxy firewall?

Correct : A. application

37. Encryption Strength is based on

Correct : D. all of the above

38. GCD(a,b) = GCD(b,a mod b)

Correct : A. true

39. All groups satisfy properties

Correct : C. g-i to r-v

40. An Abelian Group satisfies the properties

Correct : A. g-i to g-v

41. A Ring satisfies the properties

Correct : D. g-i to r-iii

42. A Ring is said to be commutative if it also satisfies the property

Correct : D. r-iv

43. An ‘Integral Domain’ satisfies the properties

Correct : C. g-i to r-vi

44. Does the set of residue classes (mod 3) form a group with respect to modular addition?

Correct : A. yes

45. For the group Sn of all permutations of n distinct symbols, what is the number of elements in Sn?

Correct : D. n!

46. a(b+c) = ac+bc is the representation for which property?

Correct : D. r-iii

47. a.(b.c) = (a.b).c is the representation for which property?

Correct : A. g-ii

48. AES uses a                             bit block size and a key size of                        bits.

Correct : D. 128; 128, 192, or 256

49. Like DES, AES also uses Feistel Structure.

Correct : B. false

50. Which one of the following is not a cryptographic algorithm?

Correct : A. jupiter

51. If the key is 110100001, the output of the SP network for the plaintext: 101110001 is

Correct : B. 110101110

52. What is the number of possible 3 x 3 affine cipher transformations

Correct : D. 1344

53. What is the expanded key size of AES-192?

Correct : C. 52 words

54. In affine block cipher systems if f(m)=Am + t, what is f(m1+m2+m3) ?

Correct : C. f(m1) + f(m2) + f(m3)

55. The 4×4 byte matrices in the AES algorithm are called

Correct : A. states

56. If the block size is ‘s’, how many affine transformations are possible ?

Correct : C. 2ss (2s-1)(2s-2)(2s-22) ………(2s-2(s-1))

57. For the AES-128 algorithm there are                        similar rounds and                       round is different.

Correct : B. 9 ; the last

58. The DES Algorithm Cipher System consists of                            rounds (iterations) each with a round key

Correct : D. 16

59. DES follows

Correct : C. feistel cipher structure

60. Every cyclic group is            .

Correct : D. an abelian group

61. In the DES algorithm the round key is                        bit and the Round Input is                            bits

Correct : A. 48, 32

62. is not a binary operation on the set of natural numbers.

Correct : C. difference

63. In the DES algorithm the Round Input is 32 bits, which is expanded to 48 bits via

Correct : A. scaling of the existing bits

64. Which of the following is group under multiplication?

Correct : B. q-{0}

65. The Initial Permutation table/matrix is of size

Correct : D. 8×8

66. The number of unique substitution boxes in DES after the 48 bit XOR operation are

Correct : A. 8

67. The DES algorithm has a key length of

Correct : C. 64 bits

68. What is the size of the key in the SDES algorithm?

Correct : D. 10 bits

69. The Plaintext for the Ciphertext 10100101, given that the key is 0010010111 is

Correct : B. 110110

70. Assume input 10-bit key, K: 1010000010 for the SDES algorithm. What is K1?

Correct : A. 10100100

71. Assume input 10-bit key, K: 0010010111 for the SDES algorithm. What is K2?

Correct : A. 11101010

72. Which of the following is a mode of operation for the Block ciphers in cryptography?

Correct : D. all of the above

73. Which of the following modes of operations can be followed for both stream ciphers as well as block ciphers?

Correct : C. a. cfb (cipher text feed back)

74. The Plaintext for the Ciphertext 00001111, given that the key is 1111111111 is

Correct : C. 11111111

75. Which one of the following RC4 algorithm not used in?

Correct : C. ftp

76. Till when was the RC4 algorithm kept a secret?

Correct : D. 1994

77. The Plaintext for the Ciphertext 00100010, given that the key is 1111111111 is

Correct : D. 1001100

78. The man-in-the-middle attack can endanger the security of the Diffie-Hellman method if two parties are not

Correct : A. authenticated

79. RSA is also a stream cipher like Merkel-Hellman

Correct : A. true

80. Rabin Cryptosystem is a variant of the Elgamal Cryptosystem

Correct : B. false

81. In RSA, Ф(n) = in terms of p and q

Correct : C. (p-1)(q-1)

82. In Asymmetric Key Cryptography, the two key, e and d, have a special relationship to

Correct : D. each other

83. Using Rabin cryptosystem with p=23 and q=7 ,Encrypt P=24 to find ciphertext. The Cipher text is

Correct : D. 12

84. For RSA to work, the value of P must be less than the value of

Correct : C. n

85. Session keys are transmitted after being encrypted by

Correct : C. master keys

86. Which Cryptographic system uses C1 = (e1r) mod p and C1 = (e2r x P) mod p at the encryption side?

Correct : A. elgamal

87. The certificate message is required for any agreed-on key exchange method except

Correct : B. anonymous diffie- hellmanc

88. Sender chooses p = 107, e1 = 2, d = 67, and the random integer is r=45. Find the plaintext to be transmitted if the ciphertext is (28,9)

Correct : C. 66

89. In Asymmetric key Cryptography, although RSA can be used to encrypt and decrypt actual messages, it is very slow if the message is

Correct : B. long

90. Which of the following is not a type of symmetric-key cryptography technique?

Correct : C. diffie hellman cipher

91. In Elgamal cryptosystem, given the prime p=31,Choose e1= first primitive root of p and d=10, calculate e2

Correct : C. 25

92. How many bytes of the secret key is generated using Diffie-Hellman encryption/decryption scheme?

Correct : A. 256

93. Computation of the discrete logarithm is the basis of the cryptographic system

Correct : C. diffie-hellman key exchange

94. In Elgamal cryptosystem, given the prime p=31,Encrypt the message “HELLO”; use 00 to 25 for encoding. The value of C2 for character ‘O’ is

Correct : A. 9

95. What is the block size of RC6 Feistel block cipher?

Correct : B. 128 bits

96. What is the general equation for elliptic curve systems

Correct : D. y2+b_1 xy+b_2 y=x3+a_1 x2+a_2 x+a_3

97. USENET falls under which category of public key sharing?

Correct : A. public announcement

98. In Singular elliptic curve, the equation x^3+ax+b=0 does           roots

Correct : A. does not have three distinct

99. The value of 52003 mod 7 is(use fermat's theorem)

Correct : A. 3

100. Elliptic curve cryptography follows the associative property

Correct : A. true